1. Field of the Invention
This invention relates to electrochemical devices, such as lithium ion electrodes, and methods for making such devices. Specifically, this invention relates to high performance lithium ion electrodes having well-controlled and organized nanostructures, and methods of using electric fields to induce the assembly of particles to form such electrodes.
2. Description of the Related Art
Lithium-ion batteries have extremely favorable electrical storage and discharge characteristics and occupy a large and growing market. The total world market for lithium-ion batteries was $9.61 billion in 2009 and estimated to be $31.55 billion by 2016 (http://www.frost.com/c/10077/sublib/research-pdf.do?catId=N76F-27-00-00-00). In the automotive sub-market, 2010 saw revenues of $502 million and an expectation of $10.49 billion by 2016 (http://www.frost.com/c/10077/sublib/research-pdf.do?catId=N9E7-01-00-00-00). For many years, lithium-ion batteries have been used extensively in consumer electronics such as laptop and camera batteries. There is also increasing popularity for use in transportation, specifically electric vehicles (e.g., Tesla Motors) and aviation (e.g., Boeing 787), due to size, weight, and charge improvements over other technologies such as nickel-based batteries.
However, lithium batteries can be the subject of safety concerns due to their flammability if mishandled or poorly designed, and the impact of safety events could lead to scares about their usage, as in the Boeing 787 incidents in early 2013. Nevertheless, the significant advantages offered by lithium batteries appear to overcome concerns as publicity from adverse events subside.
Improving availability of the electrode's active material to the battery's electrolyte is a popular method of improving battery performance. Traditional processes included manual grinding of active material and binding in a solution to encourage homogeneity through random mixing, leading to even availability of active material on the electrode surface. Current techniques include combining nanoparticles of active material with conductive coating, nanowires, and mesoporous structures with embedded active material that allows for electrolyte penetration, and thus active material availability beyond the surface of the electrode.
Needed in the art is a technology for enhancing the rate capability, energy density, and cycling life of the battery and reducing cost. Specifically, needed in the art is a technology targeting the efficient mass manufacturing of lithium-ion battery electrodes with improved electrical characteristics and lower manufacturing costs.